The Israeli prime minister, Binyamin Netanyahu, has warned that if the US fails to set clear "red lines" for Iran over its nuclear programme, it cannot "place a red light" in front of Israel should the Jewish state decide to launch a military strike. "Those in the international community who refuse to put red lines before Iran don't have a moral right to place a red light before Israel," Netanyahu said on Tuesday, following clear indications from the US that it would not be bounced into hardening its position. Israel has been pressing the US to clarify the point at which it would take military action rather than allow the Iranian nuclear programme to advance. Some observers believe that this has been the primary aim of hawkish rhetoric from Netanyahu and his defence minister, Ehud Barak, over recent months.

Last week, the US secretary of state, Hillary Clinton, refused to engage on the "red lines" question. "We're not setting deadlines," she said in an interview. Her comment was reinforced on Monday by the state department spokeswoman Victoria Nuland, who said: "It is not useful to be … setting deadlines one way or another" or to outline "red lines". She added: "[President Obama] has said again and again, unequivocally, that we will not allow Iran to obtain a nuclear weapon." But continued talk about specifics was "not helpful for the diplomacy".

On Tuesday, the US defence secretary, Leon Panetta, estimated that the US would have more than a year to take action against Iran if it decided to proceed with making a nuclear weapon. "It's roughly about a year right now. A little more than a year. And so … we think we will have the opportunity once we know that they have made that decision to take the action necessary to stop [Iran]," Panetta said on CBS's This Morning programme.

The US had the capability to prevent Iran from building an atomic bomb, he added. "We have the forces in place to be able to not only defend ourselves, but to do what we have to do to try to stop them from developing nuclear weapons," he said.

Barak appears to have softened his earlier hawkish statements on the potential need for Israel to act alone in stopping the Iranian nuclear programme. Last week he hinted that Israel would not defy its "most important ally".

Most of Israel's current and former military and intelligence establishment is believed to oppose unilateral action in the face of US opposition.